No side button, but it does include a ballpoint pen. Not for me, as it can’t compete with a two pen LAMY AL-star EMR and multi-pen (four colours and a mechanical pencil) combo that I carry. Might be good for some.
Which multi-pen do you carry? Is it the Kentaur? (I’ve been debating getting that, but still rocking the Skilcraft B3 Aviator I picked up to replace the Rotring Quattro which the young lady my daughter bumped into ran into drove away w/)
The Pilot 4+1. I have a thing for the Wood line of them (4x the price). I also sometimes use a Uni (Mitsubishi) Jetstream 4&1, but I find their bodies to be weaker and to break more easily. They both appear to be Japan exclusives though.
I used a Pilot Coleto for a short while (customisable colours), but the build quality is terrible.
Oddly, my favourite pen of all is the export Pilot V5 Hi-Techpoint that you can’t easily get in Japan. They have a nasty tendency to leak, especially if taken on planes though.
Not really a Western pen fan other than LAMY (but I still preferred by Pilot V5 over my classmates’ LAMYs at school, and had a gorgeous transparent Pilot fountain pen that sadly got sat on). Pencils on the other hand… Staedtler are my go to (nice finepoint pens too, mind), but for some luxury, especially colours, you can’t beat Derwent. This set is my absolute favourite.